Peel ply masking device for an adhesive bonded attachment

ABSTRACT

A peel ply conformable masking device for protectively overlying a pre-cleaned bonding surface of an adhesive attachment adapted for bonded affixation to a selected substrate, such as an adhesive attachment of the type disclosed in U.S. Pat. Nos. 5,013,391 and 6,773,780 having a bonding surface circumscribing a temporary attachment member for holding the attachment against the substrate for the duration of a bonding agent cure time. The bonding surface of the adhesive attachment is pre-cleaned as by sand blasting and/or etching, and the masking device comprising a peel-off film carrying a thin layer of a peel-off adhesive is placed thereover to prevent contamination thereof. The masking device includes at least one aperture surrounding the temporary attachment member, and further includes at least one outwardly protruding and easily grasped pull tab for facilitated peel-off separation from bonding surface immediately prior to bonded affixation to the selected substrate.

BACKGROUND OF THE INVENTION

This invention relates generally to improvements in and to adhesiveattachments of the type designed for bonded affixation to a selectedsubstrate, such as an adhesive attachment of the type disclosed in U.S.Pat. Nos. 5,013,391 and 6,773,780 having a bonding surfacecircumscribing a temporary attachment member which holds the attachmentbonding surface against the substrate for the duration of a bondingagent cure time. More specifically, this invention relates to aprotective peel-off masking device for overlying a pre-cleanedattachment bonding surface to safeguard the bonding surface againstundesired contamination prior to installation onto the selectedsubstrate.

Adhesive bonded attachments are generally known in the art forconnecting a selected component such as a threaded nutplate or athreaded bolt onto a selected substrate such as a panel or other framecomponent in an aerospace or automotive application or the like. Suchadhesive attachments typically define a bonding surface adapted toreceive a selected curable bonding agent, whereupon the bonding surfaceis pressed against the selected substrate for the duration of bondingagent cure time. In preferred attachment designs, a temporary attachmentmember is provided for temporary connection to or engagement with thesubstrate in a manner functioning to urge or draw the bonding surfacefirmly against the substrate until the bonding agent is substantiallycompletely cured. As a result, the adhesive bonded attachment is affixedto the substrate with a substantially optimized adhesive attachmentforce.

In one such adhesive attachment design, as disclosed in U.S. Pat. No.5,013,391 which is incorporated by reference herein, a nutplate assemblyincludes a threaded nut carried by a nutplate base which defines thebonding surface for adhesive bonded attachment to the substrate. Thethreaded nut additionally carries a resilient fixture pin having a sizeand shape to be pulled into and bindingly engage an opening formed inthe substrate. This fixture pin thus comprises the temporary attachmentmember circumscribed by the bonding surface on the nutplate base. Thefixture pin functions to draw the bonding surface of the nutplate basefirmly against the substrate for the duration of a bonding agent curetime, resulting in strong adhesive attachment of the nutplate base tothe substrate. After the bonding agent cures, the resilient fixture pincan be pulled through the substrate opening and separated from thethreaded nut. Subsequently, the threaded nut is exposed through thesubstrate opening for appropriate assembly with a suitable threadedfastener or the like.

In another adhesive attachment design, as disclosed in U.S. Pat. No.6,773,780 which is also incorporated by reference herein, a threadedfastener such as a headed bolt or screw is carried by a generallyannular mounting base defining the bonding surface for adhesiveaffixation to a selected substrate. In this design, the fastener headcomprises the temporary attachment member circumscribed by the bondingsurface on the mounting base. The fastener head carries a pressuresensitive adhesive or the like suitable for temporary or impermanentconnection to the substrate. The thus-adhered fastener head cooperateswith one or more resilient spring-like structures to apply a positiveforce to the mounting base in a direction pressing the bonding surfacethereon against the substrate for the duration of a bonding agent curetime. Once again, this produces a strong adhesive bonded attachment ofthe mounting base to the substrate, which in turn supports and retainsthe fastener relative to the substrate.

While such adhesive bonded attachments of the above-described typesbeneficially secure the nutplate or fastener or other attachmentcomponent to the substrate with a strong adhesive bonding force, theactual or empirical bonding force can be adversely impacted by thecondition and/or cleanliness of the bonding surface at the time ofinstallation onto the substrate. In this regard, the bonding surface isnormally pre-cleaned during product manufacture as by sand blastingand/or surface etching, to remove any particulate debris and further topassivate the bonding surface for optimum subsequent bond strengthattachment with the selected bonding agent. However, despite suchsurface pre-cleaning, some bonding surface materials such as certainmetals may exhibit varying degrees of oxidation contamination dependingupon the time delay between product manufacture and subsequentinstallation of the adhesive attachment onto a substrate. Alternately,or in addition, post-production contamination of the bonding surface canbe attributable to other factors, such as exposure of the bondingsurface to dirt and dust, and/or the course of human handling prior toinstallation. Any or all of these factors can contribute to a reducedbond strength attachment force between the adhesive attachment and thesubstrate. To avoid this problem, it has sometimes been necessary tore-clean the bonding surface immediately prior to installation of theadhesive attachment onto the substrate.

There exists, therefore, a need for improvements in and to adhesivebonded attachments particularly with respect to an improved device ormethod for safeguarding a pre-cleaned attachment bonding surface againstundesired post-production contamination in the course ofpre-installation shipment, handling and/or storage. The presentinvention fulfills these needs and provides further related advantages.

SUMMARY OF THE INVENTION

In accordance with the invention, a relatively simple yet highlyeffective masking device is provided for mounting onto an adhesivebonded attachment, preferably in the course of attachment production,wherein the masking device effectively overlies and safeguards apre-cleaned attachment bonding surface against undesired post-productioncontamination which could otherwise interfere with adhesive bondedaffixation of the attachment onto a selected substrate. The maskingdevice comprises a relatively thin and somewhat resilient film plyconstructed from a substantially fluid-impervious material. The film plyoverlies the attachment bonding surface in substantially hermeticallysealed and intimate conformal relation therewith, as by means of aselected peel-off pressure sensitive adhesive or the like. Immediatelyprior to installation onto the selected substrate, the film ply andadhesive means are peeled away to expose the pre-cleaned attachmentbonding surface to receive a selected curable bonding agent preparatoryto installation onto the substrate.

In a preferred form, the adhesive attachment includes the pre-cleanedbonding surface in a configuration substantially circumscribing orsurrounding a temporary attachment member, of the general type disclosedin U.S. Pat. Nos. 5,013,391 and 6,773,780. The masking device comprisingthe film ply and associated peel-off adhesive means is constructed in ashape for substantially matingly overlying the bonding surface, wherebythe masking device also circumscribes the temporary attachment member,i.e., the masking device has at least one aperture formed therein toaccommodate pass-through reception of the temporary attachment member.In addition, the film ply defines at least one pull tab which projectsoutwardly beyond a periphery of the bonding surface for facilitatedpeel-off separation of the masking device immediately prior toattachment installation onto the substrate. The pull tab, in thepreferred form, also projects outwardly beyond the associated peel-offadhesive means for sealably securing the film ply over the bondingsurface.

Preferred materials for the film ply comprise relatively thin polyimideor polyester film material having suitable substantiallyfluid-impervious or gas-impervious properties, and preferably having athickness on the order of about 0.001 inch to provide sufficienthermetically sealed conformance with non-planar bonding surfaceconfigurations, and also to provide sufficient stretch capacity forfacilitated peel-off separation in otherwise relatively close-fitrelation with other attachment components such as the temporaryattachment member. Preferred peel-off adhesive materials for use withthe film ply include acrylic and silicone-based adhesives, preferablyhaving a highly cross-linked and substantially cured construction toavoid deposit of any significant residual adhesive material on theassociated attachment bonding surface following peel-off separation ofthe masking device. In the most preferred form, the peel-off adhesivematerial used with the film ply is compatible with the bonding agentapplied subsequently to the exposed bonding surface, so that anyresidual adhesive material remaining on the bonding surface aftermasking device separation will not adversely impact attachment bondstrength affixation to the substrate.

Other features and advantages of the present invention will becomeapparent from the following more detailed description, taken inconnection with the accompanying drawing which illustrate, by way ofexample, the principals of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate the invention. In such drawings:

FIG. 1 is a perspective view of an exemplary adhesive bonded attachmentin the form of a nutplate assembly for adhesive bonding onto asubstrate, wherein a nutplate base carries a peel ply masking deviceembodying the novel features of the invention;

FIG. 2 is a side elevation view of the nutplate assembly of FIG. 1, andillustrating peel-off removal of the masking device to expose a bondingsurface on the nutplate base;

FIG. 3 is a fragmented perspective view showing placement of an adhesivebonding agent onto the exposed bonding surface of the nutplate base;

FIG. 4 is a fragmented perspective view depicting bond-on placement ofthe nutplate assembly of FIG. 3 onto a selected substrate;

FIG. 5 is an enlarged and fragmented sectional view taken generally onthe line 5-5 of FIG. 4;

FIG. 6 is an enlarged and fragmented plan view showing a succession ofpeel ply masking devices of the present invention carried on a linertape;

FIG. 7 is a cross sectional view taken generally on the line 7-7 of FIG.6;

FIG. 8 is an underside perspective view showing an alternative adhesivebonded attachment in the form of a threaded stud carried by a mountingbase defining an attachment bonding surface, and further illustrating apeel ply masking device in accordance with one alternative preferredform of the invention for normally covering and masking the attachmentbonding surface;

FIG. 9 is an underside perspective view of the threaded stud andmounting base-type attachment shown in FIG. 8, and further depictingplacement of an adhesive bonding agent onto the bonding surface of themounting base, following peel-off removal of the masking device;

FIG. 10 is a fragmented vertical sectional view showing initialplacement of the attachment of FIG. 9 onto a selected substrate; and

FIG. 11 is a fragmented vertical sectional view similar to FIG. 10, butillustrating secure bonded affixation of the attachment to thesubstrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in the exemplary drawings, a peel ply masking device referredto generally in FIGS. 1-2 and 6-7 by the reference numeral 10 isprovided for protectively overlying a pre-cleaned bonding surface 12(FIG. 5) of an adhesive attachment 1 4, such as the illustrativenutplate assembly shown in FIGS. 1-5. The adhesive attachment 14 isdesigned for relatively high strength adhesive bonded affixation onto aselected substrate 1 6. The peel ply masking device 10 of the presentinvention effectively safeguards the attachment bonding surface 12against undesired post-production contamination which could otherwiseadversely affect the bond-on affixation strength.

The illustrative adhesive attachment 1 4 shown in FIGS. 1-5 comprises anutplate assembly of the type disclosed in U.S. Pat. No. 5,013,391,which is incorporated by reference herein. As shown, this nutplateassembly comprises a threaded nut 18 or the like carried preferably withat least some floating or freedom of movement by a nutplate base 20having an underside surface defining the bonding surface 12. A resilientfixture pin 22 is carried by the threaded nut 18 to include a tailsegment 23 protruding through the nutplate base 20 and projectingoutwardly or downwardy therefrom. This fixture pin 22 comprises atemporary attachment member for short-term retention of the nutplateassembly 14 on the substrate 16 for the cure time of the selectedbonding agent 24.

In use, again as described in the above-referenced U.S. Pat. No.5,013,391, a curable bonding agent 24 is applied directly onto thenutplate base bonding surface 12, as by means of a suitable agentapplicator 26 as viewed in FIG. 3. The nutplate assembly 14 is thenseated upon the selected substrate 16, such as a panel or framecomponent of an aircraft or automotive structure or the like, with thetail 23 of the fixture pin 22 extending through an opening 28 (FIG. 5)formed in the substrate 16. In this regard, the fixture pin 22 is sizedfor pull-through reception through the substrate opening 28, with aradially enlarged shoulder segment 30 on the fixture pin 22 bindinglyengaging within the substrate opening 28. This binding engagementbetween the fixture pin and the substrate enables the fixture pin toapply a pulling or drawing force to the nutplate assembly 14, resultingin a positive force urging the bonding surface 12 toward the substrate16. This arrangement effectively draws the bonding surface 12 towardintimate seated relation with the substrate, as the bonding agent 24therebetween is extruded outwardly to achieve a minimum bond linethickness with a maximum bond strength attachment. The fixture pin 22remains engaged with the substrate 16 for the duration of a bondingagent cure time, after which the fixture pin 22 can be separated fromthe adhesively bonded components by pulling outwardly on the tailsegment 23 (FIG. 4).

The peel ply masking device 10 of the present invention effectivelyoverlies and seals the bonding surface 12 of the nutplate assembly 14 toprevent undesired post-production contamination thereof. The maskingdevice 10 is quickly and easily removable from the bonding surface 12 bysimple peel-off separation therefrom, immediately prior to installationonto the substrate 16.

More particularly, as shown best in FIGS. 6-7, the peel ply maskingdevice 10 comprises a film ply 32 formed from a selected material whichis substantially impervious to fluids including but not limited to air.This film ply 32 may be constructed, in accordance with preferred forms,from a selected polymer-based material such as a polyimide or polyesterfilm material having a relatively thin structure and sufficient inherentflexibility and/or resiliency to accommodate close-fit and substantiallysealed overlying conformance with an associated bonding surface 12 whichmay exhibit deviations from a true planar shape. In this regard, apreferred thickness for the film ply 32 is on the order of about 0.001inch.

The film ply 32 is pre-cut to define a main body segment 34 having asize and shape for substantially mated overlying fit with the associatedbonding surface 12. In this regard, as viewed best in FIG. 6, the bodysegment 34 of each film ply 32 is shown with a generally rectangulargeometry having suitable length and width dimensions for conformablyoverlying the generally rectangular shape of the bonding surface 12 onthe underside of the associated nutplate base 20 (FIGS.1 -5). Inaddition, since the bonding surface 12 circumscribes or surrounds acentral port 36 (FIG. 5) formed in the nutplate base 20 to accommodatepassage of the fixture pin 22, the body segment 34 of the film ply 32additionally includes at least one aperture 38 for alignment therewith.

A peel-off adhesive material 40 is provided in a thin layer underlyingthe peel ply 32, wherein this peel-off adhesive material 40 is designedfor quickly and easily mounting the masking device 10 onto the bondingsurface 12 in a conformably fit, substantially hermetically sealedmanner. The peel-off adhesive material 40 comprises, in one preferredform, a pressure sensitive adhesive preferably such as an acrylic orsilicone-based adhesive material that is highly cross-linked andsubstantially cured to avoid deposit of any significant residualadhesive material on the associated bonding surface 12 followingpeel-off separation from the bonding surface 12 substantially as a unitwith the film ply. In the most preferred form, the peel-off adhesivematerial 40 used with the film ply 32 is compatible with the bondingagent 24 applied subsequently to the exposed bonding surface, so thatany residual adhesive material remaining on the bonding surface aftermasking device separation will not adversely impact attachment bondstrength affixation to the substrate.

The film ply 32 is additional formed to include at least one pull tab 42protruding outwardly from the main body segment 34, with theillustrative drawings shown a pair of such pull tabs 42 projectingoutwardly from opposite sides of the main body segment 34. These pulltabs 42 are, in the preferred form, associated with an underlying paperliner 43 (FIG. 7) to prevent adherence to the attachment 14 or otherstructure.

The masking device 10, as described, may be produced in tape form as byproducing a succession of masking devices 10 adhered by means of thepeel-off adhesive material 40 to one side of an elongated flexible tapecarrier strip 44 as viewed in FIG. 6. In this form, the masking devices10 may be subjected to a suitable punch-cut step for producing thecentral apertures 38 respectively therein (and also through the carrierstrip 44). In addition, in this form, the masking devices 10 can bepeel-away separated from the tape carrier strip 44 manually or by meansof automated production equipment for individual mounting onto anutplate base bonding surface 12 as viewed in FIGS. 1-2.

In such mounted position, each masking device 10 effectively overliesand seals the bonding surface 12, which has been pre-cleaned andpassivated as by appropriate sand blasting and/or surface etching steps.The central aperture 38 in each masking device 10 is aligned with theport 36 in the bonding surface 12 to accommodate close-fit passage ofthe fixture pin 22 in a non-interfering manner. The paper-lined pulltabs 42 project outwardly from opposite ends of the bonding surface 12for easy manual grasping and peel-off removal of the masking device 10(FIG. 2), including the film ply 32 and associated peel-off adhesivematerial 40, with the film ply 32 having sufficient flexibility orresilience to pull away from the fixture pin 22 despite close-fittolerance therewith. As a result, the pre-cleaned and mask-protectedbonding surface 12 is now exposed for application of the bonding agent24 (FIG. 3) and mounting onto the substrate 16 (FIGS. 4-5) as previouslydescribed.

FIGS. 8-11 depict the masking device of the present invention in onealternative preferred form, wherein components corresponding instructure or function with those previously shown and described hereinare identified by common reference numerals increase by 100. As shown,the modified masking device 110 is configured for use with analternative adhesive attachment 114, such as a threaded fastener 118carried by a mounting base 120 defining a bonding surface 112 foradhesive bonded affixation onto a selected substrate 116. Suchalternative adhesive attachment 114 is shown and described in furtherdetail in U.S. Pat. No. 6,773,780, which is also incorporated byreference herein.

More particularly, the adhesive attachment 114 comprises the threadedfastener 118 such as a bolt or screw having an enlarged head 122 formingthe temporary attachment member for short-term securement to thesubstrate 116. As shown, the fastener head 122 carries a pressuresensitive adhesive 60 of the like, in a position disposed generallycentrally within and substantially surrounded or circumscribed by thebonding surface 112 of generally annular shape formed on the undersideof the mounting base 120. In use, a selected bonding agent 124 isapplied as by means of an applicator 126 (FIG. 9) to the bonding surface112, followed by pressed seating of the mounting base 120 firmly againstthe substrate 116. The fastener 118 is then pressed firmly against thesubstrate 116, as indicated by arrow 62 in FIG. 10, to advance theadhesive-coated head 122 of the fastener into temporary adhesiveconnection with the substrate 116. The fastener head 118 thus applies apulling or drawing force to a spring member 64 coupled between thefastener head and the mounting base 120, for purposes of drawing themounting base 120 and the bonding surface 112 thereon firmly toward thesubstrate 116 for the duration of a bonding agent cure time. Once again,as in the prior-discussed embodiment, this drawing force beneficiallycauses the bonding agent 124 to be extruded outwardly to achieve aminimum bond line thickness with a maximum bond strength attachment.

The modified masking device 110 is constructed in generally the samemanner as previously shown and described herein, to include a film ply132 shaped for conformal overlying placement to protectively cover thebonding surface 112. In this regard, the film ply 132 includes a centralbody segment 134 having a peel-off adhesive material 140 lining one sidethereof for sealed overlying placement covering the bonding surface 112,with at least one aperture 138 formed therein for accommodating thefastener head 122 and associated adhesive material 60 and spring member64 in a non-interfering manner. The film ply 132 further includes atleast one outwardly protruding pull tab 142, such as the pair ofoppositely projecting pull tabs 142 shown in FIG. 8, wherein these pulltabs 142 are not associated with or lined by the peel-off adhesivematerial 140.

The modified masking device 110 thus also seals and protects the bondingsurface 112 against post-production contamination. The masking device110 is quickly and easily separated from the bonding surface 112immediately prior to installation of the attachment 114 onto thesubstrate 116.

Although various embodiments and alternatives have been described indetail for purposes of illustration, various further modifications maybe made without departing from the scope and spirit of the invention.Accordingly, no limitation on the invention is intended by way of theforegoing description and accompanying drawings, except as set forth inthe appended claims.

1. In an adhesive attachment having a bonding surface for adhesiveattachment to a substrate, a peel ply masking device, comprising: aconformable film ply formed from a substantially fluid imperviousmaterial, and having a body segment with a size and shape forsubstantially overlying the attachment bonding surface; and a peel-offadhesive material carried by said film ply body segment for removablymounting said body segment onto the attachment bonding surface inintimate, substantially overlying fit relation therewith to preventcontamination thereof; said film ply and said peel-off adhesive materialbeing removable substantially as a unit from the attachment bondingsurface.
 2. The peel ply masking device of claim 1 wherein said film plyfurther includes at least one pull tab projecting outwardly from saidbody segment.
 3. The peel ply masking device of claim 2 wherein said atleast one pull tab projects outwardly beyond said peel-off adhesivematerial.
 4. The peel ply masking device of claim 1 wherein said filmply comprises a material selected from the group consisting essentiallyof polyimide and polyester film material.
 5. The peel ply masking deviceof claim 4 wherein said film ply has a thickness of about 0.001 inch. 6.The peel ply masking device of claim 1 wherein said peel-off adhesivematerial comprises a highly cross-linked pressure sensitive adhesivematerial.
 7. The peel ply masking device of claim 1 wherein saidpeel-off adhesive material is selected from the group consistingessentially of acrylic and silicone adhesives.
 8. The peel ply maskingdevice of claim 1 further including a curable bonding agent foradhesively bonding the attachment bonding surface to a substrate, andfurther wherein said peel-off adhesive material comprises an adhesivematerial compatible with the curable bonding agent.
 9. The peel plymasking device of claim 1 wherein the adhesive bonding surfacesubstantially circumscribes a temporary attachment device, and furtherwherein said film ply has a central aperture formed therein.
 10. Anadhesive attachment assembly, comprising: an adhesive attachment devicedefining a bonding surface for adhesive attachment to a substrate; and apeel ply masking device including a conformable film ply formed from asubstantially fluid impervious material, and having a body segment witha size and shape for substantially overlying said bonding surface; saidpeel ply masking device further including a peel-off adhesive materialcarried by said film ply body segment for removably mounting said bodysegment onto the attachment bonding surface in intimate, substantiallyoverlying fit relation therewith to prevent contamination thereof; saidfilm ply and said peel-off adhesive material being removablesubstantially as a unit from the attachment bonding surface.
 11. Theadhesive attachment assembly of claim 10 wherein said film ply furtherincludes at least one pull tab projecting outwardly from said bodysegment.
 12. The adhesive attachment assembly of claim 11 wherein saidat least one pull tab projects outwardly beyond said peel-off adhesivematerial.
 13. The adhesive attachment assembly of claim 10 wherein saidfilm ply comprises a material selected from the group consistingessentially of polyimide and polyester film material.
 14. The adhesiveattachment assembly of claim 13 wherein said film ply has a thickness ofabout 0.001 inch.
 15. The adhesive attachment assembly of claim 10wherein said peel-off adhesive material comprises a highly cross-linkedpressure sensitive adhesive material.
 16. The adhesive attachmentassembly of claim 10 wherein said peel-off adhesive material is selectedfrom the group consisting essentially of acrylic and silicone adhesives.17. The adhesive attachment assembly of claim 10 further including acurable bonding agent for adhesively bonding the attachment bondingsurface to a substrate, and further wherein said peel-off adhesivematerial comprises an adhesive material compatible with the curablebonding agent.
 18. The adhesive attachment assembly of claim 10 whereinthe adhesive bonding surface substantially circumscribes a temporaryattachment device, and further wherein said film ply has a centralaperture formed therein.
 19. A peel ply masking device assembly,comprising: an elongated carrier tape; and a succession of individualpeel ply masking devices on said carrier tape, each of said peel plymasking devices comprising a film ply including a body segment, and apeel-off adhesive material interposed between said body segment and saidcarrier tape; said peel ply masking devices being individually separablefrom said carrier tape for removable mounting of said body segmentthereof in intimate, substantially overlying fit onto a bonding surfaceof an adhesive attachment to prevent contamination of said bondingsurface.
 20. The peel ply masking device assembly of claim 19 whereinsaid film ply further includes at least one pull tab projectingoutwardly from said body segment.